The 2001 S55 AMG is a hand-built supercharged monster with 493 hp, but the M113K engine's early years suffer from serious cylinder bore wear issues that can destroy engines prematurely. When maintained properly, the drivetrain is strong, but this year falls squarely in the danger zone for catastrophic engine failure.
Cylinder Bore Wear and Piston Ring Failure (M113K Engine)
Common · high severity
Typical onset: 60,000-120,000 mi
Symptoms: Excessive oil consumption (1+ quart per 1,000 miles), Blue smoke on cold start or acceleration, Loss of compression and power, Metallic rattling from bottom end when cold, Cylinder misfire codes
Fix: Early M113K engines had inadequate nickel-silicon carbide bore coating that wears prematurely. Requires complete engine rebuild with properly sleeved cylinders, new pistons, rings, bearings, and gaskets. Engine-out job takes 25-35 hours. Some owners opt for remanufactured long-block swap at 20-24 hours labor.
Estimated cost: $12,000-18,000
Transmission Oil Cooler Line Failure
Common · high severity
Typical onset: 70,000-150,000 mi
Symptoms: Transmission fluid leaking near radiator area, Pink or red fluid puddles under front of car, Transmission slipping or delayed engagement, Milky transmission fluid (if coolant mixing)
Fix: The metal oil cooler lines corrode and crack where they connect to the radiator, causing catastrophic fluid loss. If coolant mixes with ATF, transmission failure follows. Replace both cooler lines and flush system thoroughly. 3-5 hours labor. Critical to catch early before transmission damage.
Symptoms: Harsh shifting or shift flare between gears, Limp mode activation, Transmission fault codes, No upshift past 2nd or 3rd gear, Erratic shift points
Fix: The 722.6 transmission's conductor plate (electrical control module inside the valve body) develops cracks in solder joints or shorts from fluid contamination. Requires transmission pan removal, valve body service, new conductor plate, filter, and fluid. 6-8 hours labor if caught early.
Estimated cost: $1,200-2,200
Airmatic Air Suspension Compressor and Strut Failure
Common · medium severity
Typical onset: 80,000-130,000 mi
Symptoms: Vehicle sagging on one or more corners overnight, Compressor runs constantly or excessively, Suspension fault warning on dash, Rough ride quality, Compressor overheating shutdown
Fix: Air struts develop leaks in bags or seals; compressor wears from constant cycling. Each strut replacement is 2-3 hours; compressor is 3-4 hours. Many owners eventually convert to coilover suspension ($2,500-3,500 complete) rather than chase air leaks repeatedly.
Estimated cost: $1,200-1,800 per strut, $1,500-2,000 compressor
ABC Active Body Control Hydraulic System Leaks
Occasional · high severity
Typical onset: 90,000-150,000 mi
Symptoms: Green hydraulic fluid leaks under car, ABC warning light and suspension fault messages, Vehicle sits low or uneven, Harsh ride or loss of active suspension function, Pump noise or whining
Fix: The Active Body Control system uses high-pressure hydraulics. Common leak points include front struts, accumulator spheres, and hydraulic lines. System requires specialty tools and bleeding procedure. Strut replacement 4-6 hours each; pump replacement 6-8 hours. Extremely expensive when multiple components fail.
Estimated cost: $2,500-4,000 per strut, $3,500-5,000 pump
Rear Transmission Mount Collapse
Common · low severity
Typical onset: 60,000-100,000 mi
Symptoms: Clunk when shifting from Park to Drive/Reverse, Vibration at idle in gear, Excessive driveline movement visible during throttle application, Transmission noise or whine changes with load
Fix: The fluid-filled rear transmission mount deteriorates and allows excessive drivetrain movement. Relatively straightforward replacement from underneath with transmission supported. 2-3 hours labor including subframe access.
Estimated cost: $400-700
Supercharger Snout Bearing and Clutch Wear
Occasional · medium severity
Typical onset: 100,000-150,000 mi
Symptoms: Grinding or squealing noise from supercharger area, Loss of boost pressure, Check engine light with boost system codes, Rattling on cold start that disappears when warm
Fix: The Eaton M62 supercharger's electromagnetic clutch and input shaft bearings wear over time. Requires supercharger removal, disassembly, bearing/clutch replacement, and new seals. Specialized job taking 8-12 hours. Can be combined with preventive coupler replacement.
Estimated cost: $2,000-3,500
Owner tips
Check oil consumption religiously every 500 miles — more than 1 quart per 1,000 miles means bore wear is starting
Inspect transmission cooler lines annually; replace proactively before they burst if surface corrosion visible
Use only Mercedes-approved ATF (236.14) and change every 40,000 miles despite 'lifetime fill' claims
Budget $2,000-3,000 annually for suspension repairs if keeping Airmatic; coilover conversion is viable alternative
Pre-purchase inspection MUST include compression test and leak-down test on all 8 cylinders — non-negotiable
Only buy if you can verify clean compression numbers and documented oil consumption under 1 quart per 2,000 miles, or you have $15,000 set aside for an engine rebuild — otherwise this is a financial grenade.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Fitment notes: Battery located in trunk; high-performance supercharged engine requires AGM battery with high CCA
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Every control module on the 2001-2006 Mercedes-Benz S55 AMG — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
📍 Center console, behind radio/navigation screen, or in trunk (fiber optic amplifier)
🔧 Star Diagnosis DAS/Xentry
⚠️ COMAND 2.0 or 2.5 system; navigation DVD drive common failure. Fiber optic MOST bus; requires proper termination. Coding for vehicle-specific features.
Supplemental Restraint System Control Unit (SRS)1.0 hr R&Rdealer / factory tool +0.4 hr▸ programming details
📍 Center console, under front seats, or behind center trim panel
🔧 Star Diagnosis DAS/Xentry
⚠️ Battery disconnect required; wait 90 seconds before work. Crash data must be cleared; seat occupancy sensors require calibration.
⚠️ VIN-locked; mileage stored in cluster and EIS. Replacement requires SCN coding and mileage transfer authorization from Mercedes. Part of security triangle.
Airmatic / Active Body Control (ABC)1.0 hr R&Rdealer / factory tool +0.5 hr▸ programming details
📍 Engine bay, right side near firewall, or under front passenger seat
🔧 Star Diagnosis DAS/Xentry
⚠️ Active Body Control hydraulic suspension system; requires calibration and ride height adaptation. Hydraulic fluid service often needed. System-specific to ABC-equipped S55 AMG.
Bi-Xenon Control Unit (XCU)0.8 hr R&Raftermarket tool +0.2 hr▸ programming details
📍 Behind headlight assemblies, left and right (two modules)
🔧 Star Diagnosis or Autel MaxiSys
⚠️ Bi-xenon headlight ballast and control; headlight leveling calibration required. Common failure item. Two separate modules per headlight.
📍 Trunk area, left or right side panel, near SAM-R
🔧 Star Diagnosis DAS/Xentry
⚠️ Early telematics system; analog cellular network (discontinued service). Requires dealer activation if replacing. Often non-functional due to network shutdown.
Parktronic Control Unit (PTS)0.7 hr R&Raftermarket tool +0.2 hr▸ programming details
📍 Trunk area, behind rear trim panel, or under rear bumper
🔧 Star Diagnosis or Autel MaxiSys
⚠️ Rear parking sensors; sensor calibration required. Most aftermarket tools can perform adaptation.
📍 Trunk area, near fuel tank, or integrated with SAM-R
🔧 Star Diagnosis or Autel MaxiSys
⚠️ May be integrated into SAM-R on some model years; controls fuel pump relay and pressure. Basic adaptation possible with aftermarket tools.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2001 Mercedes-Benz S55 AMG 5.4L V8 Supercharged M113K and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.